Input/output interfaces include serial interfaces such as RS-232C and Universal Serial Bus (USB). In the case of connecting a peripheral device to a host device by using the USB interface (often referred to simply as USB), a port control device performs port control by detecting a connection state of these devices.
Recently, the USB 3.1 standard has been developed, and a new USB interface called Type-C has been standardized. In inserting a plug into a socket, according to the USB Type-C interface, unlike the conventional interfaces up to USB 3.0, the plug can be inserted either way up. The Type-C connector is the so-called reversible-type connector and has characteristics of exchanging a USB signal at a maximum transmission speed of 10 Gbits/s, transmitting a video signal conforming to the standard such as DisplayPort, High-definition Multimedia Interface (HDMI) or Mobile High-definition Link (MHL), and having a power delivery function of supplying a maximum power of 100 W. The USB Type-C cable has identical plugs at both ends, and unlike most conventional USB cables, the type of the connector is not physically differentiated between Type-A and Type-B on the host device side, but the USB interface still maintains the logical relationship between a host device and a peripheral device. Therefore, the relationship between a host device and a peripheral device is determined based on connection detection and signal direction detection at the time of connection via a configuration channel provided in the Type-C cable. Note that, although connectors are referred to as a socket and a plug, the socket and the plug may also be referred to as respective connectors or as a first connector and a second connector.
Other than those described above, for example, in the power delivery function, the Type-C connector determines a voltage and a current to be actually supplied in an operation based on a power deliver protocol message exchanged via the configuration channel.
In this way, the configuration channel is used to detect a device connection and then perform a negotiation process with a device of various functions based on a communication protocol via one contact of the USB Type-C.
As described above, the configuration channel performing communication via one contact of the USB Type-C is used to detect a device connection and then perform a negotiation process with a device of various functions based on a communication protocol. There are two methods to realize these connection detection function and communication function, that is, a method of connecting an IC dedicated to the USB Type-C to the connection contact and a method of connecting a microcomputer to the connecting contact. However, the use of a dedicated IC causes an increase in cost, while the use of a microcomputer requires two connection contacts and their switch control because it is difficult to realize these two functions through the same connection contact.
The present embodiment aims to provide a port connection circuit, a port connection control method and an electronic device which can easily switch the connection detection function and the communication protocol detection function.